The present invention relates to a method of imprinting on a surface which produces a raised line imprinted lettering or design on a lightweight foam polymer material having a thin polymer laminate covering.
In the past, it has been common in the manufacture of display mounts for calendars, and the like, to provide printing on the surface of the mounts as well as on the calendar pads including conventional lithographic printing with inks. It has also been common to foil stamp display mounts, especially with gold foil stamping, which requires the feeding of a roll of colored foil paper material through a heated die and applying the heated die against the foil stamping material and against the surface being printed upon to transfer foil stamped letters or designs to the surface of the display mount board.
In a typical foil stamping operation, the board is under pressure so that there is a slight indentation in the surface, especially of soft materials, but the foil stamping can produce a desirable printing resembling gold leaf. In the art of display mounts, it has become common in recent years to seek ways to reduce the weight of the display mount and calendar pads because of the substantial increase in postage rates. Display mounts for displaying calendars are provided through various companies as part of the company's advertising, as well as through sales to the public, which requires the mailing of individual calendars. If the calendar weight can be kept within one ounce, it can then be mailed first class with one stamp. Prior display mounts, however, use heavy paperboard which is casebound in two or three layers to provide a pocket for the calendar. This increases the weight substantially and required an increase in postage. With the new postal rates, however, several techniques for reducing postage have been proposed, one of which has been to make display mounts of a foamed polymer material such as a foamed polystyrene having a surface laminate of polystyrene which does not require casebinding and which is light in weight but sufficiently strong to allow display mounts to be made with lower weight. This material can be printed on but is sensitive to heat and pressure, which destroys the laminate.
The present invention is directed towards a method in which the use of predetermined pressures, temperatures and dwell times for different colors of foil stamping on a laminate cover foamed polymer material will press the material but will produce a swelling directly under the foil coating or heated die to produce a raised letter effect and a substantially improved appearance of the imprinted material.
Typical display mounts for calendar pads and the like may be seen in my prior U.S. Pat. No. 2,355,706 for a display mount having a well in the face thereof for displaying material such as calendar pads and in U.S. Pat. Nos. 3,058,410 and 3,079,715 for an improved display mount structure and improved method for forming the display windows and display wells and display mount structures. In addition, my prior patents on display and photo mounts can be seen in U.S. Pat. No. 3,216,582; U.S. Pat. No. 3,068,139; and U.S. Pat. No. 3,002,720, which includes my patent on an aluminum hinge which allows a supporting prop or other display mount supports to be mounted with a flexible hinged panel which stays in place without the use of interconnecting tongues. Additional display mounts may be seen in my prior U.S. Pat. No. 4,285,683 for a method of making a display mount; U.S. Pat. No. 4,199,883 for a display mount; U.S. Pat. No. 4,326,906 for a display mount and method; U.S. Pat. No. 4,263,733 for a display mount with protected thermometer; U.S. Pat. No. 4,299,643 for a method of making a hinged display mount; U.S. Pat. No. 4,288,935 for a display book apparatus; and in U.S. Pat. No. 4,351,123 for a display mount and method. The present invention has the aim of providing an improved method of imprinting upon a foamed polymer sheet having a polystyrene laminate surface on one or both sides.